A second potentially serious knee injury in as many practice overshadowed some positive developments for Arizona State in its Saturday scrimmage at Sun Devil Stadium.

After watching senior receiver T.J. Simpson carted off the practice field Thursday with what is believed to be a torn ACL in his left knee, ASU's players saw senior cornerback Omar Bolden leave with what is believed to be a serious knee injury of his own two days later.

Both men were hurt on non-contact plays where their leg buckled. Bolden was able to walk off the field and into the Sun Devils' locker room on his own power, but two team sources said preliminary tests indicated a torn ACL was likely to be found on the pending MRI exam.

"When you see two guys like that go down you almost feel like not practicing," ASU coach Dennis Erickson said.

Losing either or both for the 2011 season would be a serious blow for the team many analysts have pegged a favorite to win the inaugural Pac-12 South this season.

Bolden elected to bypass the NFL Draft and instead return for a fifth year at ASU after earning unanimous first-team all-conference honors as selected by the league's coaches last season. He also is one of the top returning kick return specialists in the country, though his loss would be most felt at cornerback, where the Sun Devils have just three experienced scholarship players. Last season Bolden led ASU with three interceptions for 85 yards and seven pass deflections.

Simpson had 29 catches for 481 yards and was second on the team in yards-per-catch. Due in part to his track speed, he was perhaps the team's best vertical threat among outside receivers, and was projected to start at the split end position.

Holliday's three catches for 48 yards led the Sun Devils in the scrimmage. He also had the lone touchdown on the afternoon, hooking up with junior quarterback Brock Osweiler on a 13-yard post route over the middle out of a wishbone-variant formation.

Osweiler completed 9 of 13 pass attempts on the day for 68 yards, a composed showing that included just one questionable throw.

"I thought it went well, especially the first group," Osweiler said. "Obviously, there's little things we have to clean up, but that's normal for spring ball. But I think we're definitely progressing at the rate we need to be ready for the fall."

It was junior running back Cameron Marshall who drew the biggest applause from the crowd on a play where he got the better of junior linebacker Vontaze Burfict on a violent collision in the hole. Marshall rushed for 55 yards on just six carries, with three big gainers.

"I don't think I've ever seen anybody do that to be perfectly honest with you," Erickson said.

The collision was perhaps some modicum of payback for a now-famous collision two years ago in the Dickey Dome when Burfict put a big hit on Marshall.

"He got the upper hand that time our freshman year so I guess I got it this time," Marshall said.

While ASU's first team offense earned some praise from Erickson and a number of players on the defense had solid individual efforts including senior end Jamaar Jarrett with a tackle for loss and sack, sophomore William Sutton with a tackle for loss and forced fumbled, and freshman linebacker Carl Bradford with an interception and physical tackle, it was perhaps several new key special teams performers who made the biggest impressions.

Freshman kicker Alex Garoutte struggled mightily through the first week of spring ball before an improved practice Tuesday and solid showing Thursday. Kicking in the stadium for the first team with the first unit, Garoutte hit all three of his field goal attempts Saturday, including two from beyond 40 yards.

Not to be outdone, junior punter Josh Hubner, in his first action in the stadium, showed off an extremely impressive leg and very good consistency with numerous 60-plus yard punts in the first segment of the session.